A vehicle differential is a device employing differential gears within a housing called a differential carrier. The vehicle differential is connected to three shafts. An input shaft transmits torque and rotation from a vehicle engine into the differential gears. In turn, each of the other two shafts separately transmits a portion of the torque and rotation from the differential gears out to separate external wheels.
For lubrication of the meshing of the differential gears, the differential gears within the differential carrier are at least partially submerged in a lubricant, for example, a mineral—standard base lubricant or a synthetic—premium lubricant. In either case, the lubricant may be certified as an API GL5 classification oil or SAE J2360 standard oil, and sealed within the differential carrier housing.
As a result of initial machining of the differential and associated parts therein, along with rigorous meshing of the differential gears during the differential's operation over an extended period of time, metal particles enter the lubricant within the differential and cause friction within. In turn, the friction affects the thermal conditions by increasing the temperature within the differential, which in turn causes more wear on the associated parts.
In general, when the rear wheels of a vehicle are caused to turn or are experiencing wheel slippage, as quite often happens, an outside wheel(s) makes a larger radius than an inside wheel(s). As a result, the outside wheel goes a farther distance, moves faster, and turns more revolutions than the inside wheel. Consequently, when both wheels are on the same axle shaft, one or both wheels would have to skid or slip to make a turn. However, by applying a differential between the rear wheels, the wheels are allowed to turn at different speeds.
As a vehicle operates, the meshing and rotation of differential gears, along with the presence of metal particles in the oil of the differential, friction increases. This results in heat building up within the space, oil, and parts that comprise the differential. Consequently, the differential experiences temperature swings and potentially high operational temperatures that can lead to part failures. Hence, it would advantageous to know the thermal conditions within the differential carrier, in order to detect potential part failures and long term reliability problems.
Currently, due to high costs, there is a lack of sealing means and durability requirements for sensing temperature within the harsh environment of the differential. This is compounded by the use of slow responding sensors that are disposed directly in the differential, in order to measure conditions therein. Unfortunately, current practices result in reducing or even eliminating the effectiveness of early detection of failures within a differential.
Consequently, it would be beneficial to provide a method for temperature sensing within a differential carrier that would be based on direct and current conditions therein. This would result in a more accurate and reliable monitoring of the differential. In turn, such a method would result in a better operation of a vehicle and a better quality differential that is more reliable.